Electric bulb of the three-electrode type



Feb. 19, 1929.

0. 1.. A. M. LEBLANC ELECTRIC BULB OF THE THR EE" ELECTRQDE TYPE Filed April v, 1921 2 SheetsSheet 1 .P in.

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(1. L. A. M. LEBLANC ELECTRIC BULB OF THE THREE r ELECTRODE TYPE Filed April'Y, 1921 2 Sheefis-Sheet 2 Patented Feb. 19, 1929.

UNITED STATES exams monaan mun socrern momma :eoun vroxims, or rams, runes.

MAURICE LEBLANC, 0]! PARIS, FRANCE, ASSIGNOB TO LEXPLOITATION DES PBOCEDES MAURICE LEBLANC- ELECTRIC BULB OF THE THREE-ELECTRODE TYPE.

Application filed April 7,

This invention relates to improvements in devices known as electric bulbs of the three electrode type, wherein the current is carried either exclusively by electrons as in the audions, or likewise by the ions, as for instance in devices employing mercury vapor or containing an inert gas such as argon. These improvements have for their object to rovide a more complete action for the third electrode commonly termed the grid such as will permit a diminution of the negative potential, which it is necessary to produce upon the said grid to obtain any of the following known results. First, to completely cut off the main current passing from anode to cathode, second, to diminish the value thereof, and third, to prevent the formation of such current. 1

These improvements are applicable either in the cases where the bulb is made of glass or quartz for low power or of metal for high ower. I p The following description together with the accompanying drawings which are given by way of example show various embodiments of this invention, wherein:

Fig. 1 is a diagrammatic view of a multiple grid according to this invention.

- Fig. 2 isa diagrammatic view of a mercury vapor bulb and the connections thereof.

Fig. 3 is a diagram of the electric connections of the grid elements.

Fig. 4 is 2. dia rammatic view showing the application of t is latter arrangement to a filament bulb.

Figs. 5 and 6 show, respectively in vertical section with parts broken away and in horizontal cross-section on electric bulb constructed according to this invention.

Fig. 7 is a diagrammatic view of a three electrode bulb em tion.

Fig. 8 is a diagrammatic view of a metallic vapor bulb provided with a. device for producing a special magnetic field.

Fig. 9 is an elevational view of a bulb embodying the invention and provided with a supplementary device for increasing the mag netic field.

Fig. 10 is a horizontal section on the line 9-9 of Fig. 9, but showing a diflerent type of grid element.

odying the present inventhe line 6-6 Fig. 5, an

1921, Serial No. 459,488, and in France April 15, 1920.

Fig. 11 is a partial detail view of the grid of the bulb .shown in Figs. 5 and 6.

As shown in Fig. 1, a plurality of grid elements 1' are disposed in parallel rows wlth the elements in one row staggered relative to the elements of the other rows, so that the electronsgiven off by the cathode which shall have escaped the elements of one of the rows will be intercepted by the elements of the succeeding rows. A given electron 2 will in fact only escape a grid element if the trajectory thereof, which is adjacent a line of force of the cathode-anode field, is caused to pass through an aperture 1n the said grid element, the speed which it possesses at this moment being suifioient to permit the simple curvature of the trajectory adjacent to a grid element but without any contact with the latter. By superposing behind each other a plurality of grid elements whose apertures are not situated in coincidence, it will be almost certain that the electron will be arrested by one of these elements.

Fig. 2 shows a device applied to a mercury vapor bulb wherein the cathode is maintained in a' completely ionized state by an auxiliary arc whose circuit comprises the auxiliary anode 3', a source of continuous current 4, a resistance 5 and a self-inductance 6. At 25 is indicated the anode and at 26 the cathode. The three sets of grid grating elements are connected together and may be connected by a switch 7 with the negative pole of a battery 8 whose positive ole is connected with the cathode. It may be found advantageous to maintain differences of potential between the rid elements so that the element nearest the anode shall have the lowest potential, for the purpose ofsuperposing-in the space between grids--upon the anode-cathode electric field drawing the electrons towards the anode, an electric field in the inverse sense which acts to reduce the speed of these electrons. In Fig. 3 the three rows of grid elements are interconnected through the battcries 9 and the high resistances 10 used to obviate short circuits between the elements.

Fig. 4; shows the same disposition as applied to a vacuum bulb or inert gas bulb wherein the electrons are produced by an incandescent filament 11 forming the cathode.

At 12 is shown the anode which is usually termed the plate. Figs. 5 and 6 show a bulb of the same type. The cathode is constituted by an electron-producing filament 13 passing through the bulb on the axis thereof, the anode being formed by a concentric metal cylinder 14. This latter is connected by a rod 15 with a metal cylinder 16 which is split along a generatrix in such manner as to cnable it to be fitted upon a cylindrical portion 17 of the bulb, it being held thereon by its elasticity and contacting a flange 18. This metal assemblage is commuted by a flexible conductor 19 with a wire 27 passing through the bulb and which may be used for making the requisite electric connections.

The grids are constituted by two or more concentric sets of rigid wires 20 disposed parallel to the filament and connected by the two metal rings 21, 22. The ring 22 is supported in the same manner as previously explained with respect to the anode, and it may be electrically connected through the bulb by the conductor 29, the cylinder 30, the conductor 31 and the wire 32. Should it be desired to maintain the two sets of wires 20, 20 at different potentials, two separate metal rings are to be provided corresponding to each set. The rings, situated at one end, for instance the rings 22 and 22*. Fig. 11, are connected together by an insulating ring 33 in such manner as to form a substantial assemblage, and the said metal rings are connected respectively with the exterior by the separate conductors 29, 29.

Certain of the electrons may likewise escape along the sides of the bulb. The outer part of the bulb may be covered as shown in Fig. 7 by a metal sheet 23 which is maintained at a positive potential with references to the grids, and in this case the inner side of the tubes will become covered with a negative layer which acts to repel the electrons 2 towards the grid elements 1. By setting up a magnetic field at the same height as the gratings by means of electro-magnets, the lines of force of this field being perpendicular to the lines of force of the anode-cathode electric field, the paths of the electrons Will be deflected under the action of this field and the electrons will be more easily arrested by the grids.

Fig. 4 shows this disposition as applied to a hot filament electric bulb, and Fig. 8 as applied to a mercury vapor lamp. In the latter case, it is recognized that in order to maintain the electric arc in position it is necessary to employ a suitable self-inductance coil in the circuit thereof. The magnetic field coils 28 may be employed for this purpose, as shown in Fig. 8. The strength of this field may be increased by disposing within the bulb an iron wire core 24, as shown in elevatlon in Fig. 9 and in horizontal section in Fig. 10. In this case the grids 1 are to be given an annular form.

It IS obvious that the hereinbefore described dispositions are not limitative in their nature and that they are susceptible of all desired modifications without exceeding the limits of this invention.

Having thus described the nature of my said invention and the best means I know of carrying the same into effect, I claim:

An electron discharge device comprising a bulb, containing a cathode, an anode and a grid, said grid consisting of a plurality of spaced elements arranged in rows electrically connected together in parallel and extending transversely across the path of the electrons flowing from said cathode to said anode, the elements of one row being disposed in transversely staggered relation with respect to the elements in an adjacent row.

2. An electron discharge apparatus comprising a bulb, a cathode and an anode therein, a plurality of grids, each consisting of a plurality of spaced portions, said grids being disposed in separate spaced planes extending transversely with respect to the direction of electron flow between said cathode and said anode and with the portions of one grid disposed in staggered relation to the portions of another grid and a metallic coatin on said bulb adjacent said grid and a apted to receive a constant positive potential in the vicinity of said grids to prevent said electrons from passing through the zptitfie between said grids and the walls of the 3. Ar. lectron discharge apparatus comprisinga bulb havin a cathode, an anode, and a plurality of grids, said grids being disposed in separate spaced planes extending transversely with respect to the direction of electron flow between said cathode and said anode and designed to have a potential gradient between said grids, and a metallic coating on said bulb adjacent said grids adzlipted to receive a constant positive potentia 4. An electron discharge apparatus comprising a bulb having a cathode and an anode, and a plurality of grids, said grids being disposed in separate spaced planes extending transversely with respect to the direction of electron flow between said cathode and said anode and designed to have a potential gradient between said grids in an inverse direction with respect to the direction of electron flow between said cathode and said anode and a metal covering surrounding said bulb adjacent said grids to receive a constant positive potential.

In testimony that I claim the foregoing as my invention, I have signed my name.

CHARLES LEONARD ARMANI) MAURICE IEBLANC. 

